Aharonov-Bohm Oscillations in CVD-grown Graphene Rings

This paper presents Aharonov-Bohm (AB) oscillations in CVD-grown graphene rings. We fabricated graphene rings and characterized their conductance at 4 K under out-of-plane external magnetic fields up to +/-5.6T. Incorporating a baseline subtraction of the original conductance data enabled the observation of two-terminal conductance oscillations with a spacing of ABAB from 2.06 mT to 8.2mT, as expected for an ideal ring with a range of radii from 400 nm to 800 nm. The Fast-Fourier Transform (FFT) data showed a broad band of AB oscillation frequencies that constitute the interval of the h/e fundamental mode given by the sample geometry ranging from 122 to 488 l/T. The broad spread of FFT peaks is due to the relatively large ring width with the aspect ratio of the inner radius r1 and the width
$w$
of the ring,
$r/w\sim 1$
. The overall AB oscillations were comparable to the theoretical prediction. This work shows the AB oscillations at a significantly higher temperature (4K) despite the lower mobility of non-suspended monolayer graphene rings.